diff --git a/llvm/lib/CodeGen/TargetLoweringBase.cpp b/llvm/lib/CodeGen/TargetLoweringBase.cpp
--- a/llvm/lib/CodeGen/TargetLoweringBase.cpp
+++ b/llvm/lib/CodeGen/TargetLoweringBase.cpp
@@ -88,6 +88,11 @@
     cl::desc("Minimum density for building a jump table in "
              "an optsize function"));
 
+/// Allow overriding bzero libcall
+cl::opt<std::string>
+    OverrideBzeroLibcall("override-libcall-bzero",
+                         cl::desc("The function name for bzero"), cl::Hidden);
+
 static bool darwinHasSinCos(const Triple &TT) {
   assert(TT.isOSDarwin() && "should be called with darwin triple");
   // Don't bother with 32 bit x86.
@@ -206,6 +211,9 @@
   if (TT.isOSOpenBSD()) {
     setLibcallName(RTLIB::STACKPROTECTOR_CHECK_FAIL, nullptr);
   }
+
+  if (!OverrideBzeroLibcall.empty())
+    setLibcallName(RTLIB::BZERO, OverrideBzeroLibcall.data());
 }
 
 /// getFPEXT - Return the FPEXT_*_* value for the given types, or